1. Field of the Invention
The present invention relates to apparatus and an associated method for providing indicia on a strip identifying specific properties which depart from predetermined ranges.
2. Description of the Prior Art
It has been known to employ metal sheet to fabricate various types of products. It has also been known to inspect such sheets to make sure that the properties are within desired limits.
For certain uses such as metal cans, organic coatings are generally applied on sheets and the integrity and thickness of such coatings as well as other properties have been monitored.
Where sheets were provided in individual web form it was relatively easy to discard a particular web where defects were found. One of the problems with employing webs is that the speed which is achievable in using metal strip provided on large coils for continuous processing cannot be obtained.
It has been known to provide means for marking defective zones of metal webs and strip as well as other materials in order to provide an indication as to what portions are defective within a particular set of specifications. See, generally, U.S. Pat. Nos. 2,246,906; 2,576,043; 3,500,437; 3,188,478; 3,633,211; and 4,514,436.
U.S. Pat. No. 2,930,228 discloses a system for inspecting a coiled metal strip for various defects and placing markings corresponding to defects within certain zones on an associated tape.
U.S. Pat. No. 3,455,672 discloses a system for inspecting defects in glass and providing corresponding markings on the glass within the zones where the defects exist.
U.S. Pat. No. 3,619,578 discloses an inspection device for detecting depressions in softwood veneer by providing a light source, an associated plate member and a sensor monitoring for light passing between the plate member and the veneer.
In spite of these previously known systems, there remains a very real and substantial need for a strip detecting device which will simultaneously provide an indication on the strip in the region where a property defect exists of departures from desired properties and identification of the specific property.